Wrist straps, in particular watch straps, with a fastening device of the above-cited type have long been known. Fastening devices of this type are intended in this regard to allow wrist straps to be attached to and detached from a case in as simple a manner as possible. In relation to watch straps, in particular, there are a large number of mechanical solutions for exchanging the wrist strap attached to the watch case. This fact originates in that there are in everyday life a large number of situations in which the wearer of a wrist strap watch would like to exchange the wrist strap attached to the watch case. Examples of such situations include when the color of the wrist strap located on the watch clashes with the wearer's clothing, when a worn-out wrist strap is to be exchanged, or when the planned use of the watch is incompatible with the wrist strap currently fastened thereto, for example when a leather wrist strap is fastened to a diver's watch which the diver wishes to wear as he dives into the water or when a diver's watch is equipped with a wrist strap of normal length and is now to be worn over the diving suit and a longer wrist strap is therefore required. However, a corresponding need for wrist straps which can be exchanged rapidly and simply exists not only in relation to watches, but generally in each type of wrist strap which is mounted onto a case and has to be occasionally exchanged.
The known mechanical solutions for implementing an exchangeable wrist strap are based either on a relatively simple design principle, but require tools for attaching or detaching the wrist strap to/from the case, or allow the wrist strap to be exchanged without tools, albeit at the cost of a relatively complex design which subsequently, again, increases the production costs.
In relation to watch wrist straps which can be exchanged without tools, in particular, the system according to French patent FR 2 893 153 is for example known. The exchangeable watch strap proposed in said document uses a spring pin of variable diameter and also a corresponding end piece on the wrist strap, these two parts being shaped in a relatively complex manner and therefore being expensive to produce. In addition, this system does not prevent accidental opening and corresponding accidental detaching of the wrist strap from the watch case.
A further watch wrist strap of this type that can be exchanged without tools is presented in European patent specification EP 1 128 237. The watch wrist strap according to this document has an end piece with lateral projections which can be vertically inserted into corresponding guide channels of the lugs embodied on the watch case, a securing lever preventing the end piece from accidentally sliding out between the lugs in cooperation with a blocking face embodied laterally on the watch case. However, this design is not only based on a specific, wrist strap-side configuration of the end piece thereof, but also requires considerable alterations of the watch case or generally of the case to which the wrist strap is to be fastened. In particular, the lugs of the case have to be equipped with said guide channels; in the case of watches, this inevitably necessitates the elimination of the spring pin which is generally used there. A system of this type therefore cannot be used with most commercially available watch cases without considerable modification thereof.
Therefore, there is still a need for a relatively simply designed embodiment of an exchangeable wrist strap, which at the same time functions without tools, in particular for the watch sector, wherein this exchangeable wrist strap must satisfy the criteria with regard to aesthetics, ergonomics, wearer comfort, robustness, protection against accidental detachment, and also hygiene by way of simple cleaning of the system.